1. Field of the Invention
The present invention is related to a vapor grown carbon fiber mat and a method for fabricating the same, especially, to a vapor grown carbon fiber mat having a continuous structure.
2. Description of the Related Art
During the past decades, traditional mechanical products have been quietly substituted by 3C electronic products in our daily life. Scientists must dedicate themselves to develop products with more powerful functions, higher efficiency and faster processing velocity for satisfying the needs of speed and convenience.
All electronic products with high efficiency have to face the issues of power conversion. Powerful products need a better electronic efficiency, and accordingly, more waste heat is produced. Therefore, how to dissipate heat to maintain operating system stability is a more and more important issue.
Furthermore, lots of traditional heat-dissipating materials are gradually eliminated from the market because of the customers' critical demands for small, light and portable products.
In other words, the development of novel heat-dissipating materials is an urgent and essential issue for scientists. The basic requirements of novel heat-dissipating materials include a higher thermal conductivity and smaller size.
Some composite materials with high conductivity have been available in the market. Among those composite materials, the heat-dissipating composite material using vapor grown carbon fibers as a reinforcing material is the most potential one.
That is because the room temperature thermal conductivity of a graphitized vapor grown carbon fiber is up to 1950 W/m-K, which is approximately five times higher than that of copper, and the density of the vapor grown carbon fiber is ¼ or less than that of copper. Moreover, the room temperature resistance of the vapor grown carbon fiber is extremely low, i.e. about 0.6 μΩ·m, which is similar to that of titanium.
Among all carbon fibers, the vapor grown carbon fiber has the best thermal conductivity and resistance, and it also has good tensile stress and tension coefficient; therefore, the vapor grown carbon fiber is the best choice for developing composite materials with high thermal conductivity.
However, the length of traditional vapor grown carbon fibers is at most hundreds of microns, so that the composite materials fabricated by the traditional vapor grown carbon fibers have a lot of discontinuous scission points, which significantly restrict heat conduction and therefore reduce the thermal conductivity of the composite materials to be similar to or even lower than that of aluminum.
In view of the disadvantages of conventional technology, we provide a novel method for producing a vapor grown carbon fiber mat to fabricate carbon fiber mats having a continuous structure, which can be used for improving thermal conductivity of composite materials.